(a) Field of the Invention
The present invention relates to a digital recording system (DRS). More specifically, the present invention relates to a digital image data compression device of a digital recording system.
(b) Description of the Related Art
A digital recording system stores and transmits image information in a digital format in replacement of an analog recording system. The digital recording system is applied to various fields using image transmission techniques such as video conferencing, unmanned store management systems and traffic control systems.
In order to effectively store a huge amount of digital image data, the digital recording system compresses, stores and transmits the image data and decompresses the transmitted data into original image data and outputs the same.
Techniques for compressing the digital image data include MPEG, MJPEG, JPEG, Wavelet and Fractal systems.
The MPEG and MJPEG systems for compressing moving pictures compare pixels of the image data of a previous image with those of a present image to compress the same, and accordingly, much compression time and huge storage capacity are needed.
Also, since the image information can be lost when decompressing the compressed image data, blocks of decompressed image data are generated, and therefore the image quality becomes deteriorated, and users should pay a lot of money to use the compression methods.
The Wavelet or Fractal techniques for compressing still images per frame reduce data processing time when compressing or decompressing the data, and since the blocks are not generated, the decompressed image is clear.
However, since they only compress still images and they cannot compress moving pictures, and since there is no international standard, compatibility problems occur.
Also, in the case the digital recording system is provided to an unmanned shop or unmanned bank, the digital recording system continues to operate and compresses and stores image data even when no particular events occur in the night because of few users.
Accordingly, because of the repeated compression process, the storage capacity of the storage device is unnecessarily spent, and because of the unnecessary storing process of identical images, the lifespan of the storage device is shortened.
It is an object of the present invention to provide a device and method for effectively compressing image data.
In one aspect of the present invention, a data compressor for compressing input image data comprises an image recording controller for generating image information on respective input objects from the input image data, generating image information on a moving object using the image information, comparing the previously input image data with the presently input image data, generating new image information on the moving object and compressing the new image information; a storage unit for storing signals or data generated during compression operation of the image recording controller in a corresponding established address; and a compressed image storage unit for storing the compressed image data compressed by the control operation of the image recording controller.
In another aspect of the present invention, in a data compression method using a data compressor for compressing input image data and storing the same in an information storage unit, a data compression method comprises (a) generating image information on a moving object from the image data and comparing the image information with previously input image data; (b) generating image information on a new moving object and generating approximated image information; and (c) compressing the image information on the new moving object and the generated approximated image information and storing the compressed data in the information storage unit.